/*
   Code for JPEG decompression by the Independent JPEG Group.  Please see
   README.jpeg in the top level directory.
 */

#include "sane/sanei_jpeg.h"

typedef struct
{
	struct djpeg_dest_struct pub;	/* public fields */

	/* Usually these two pointers point to the same place: */
	char *iobuffer;		/* fwrite's I/O buffer */
	JSAMPROW pixrow;	/* decompressor output buffer */
	size_t buffer_width;	/* width of I/O buffer */
	JDIMENSION samples_per_row;	/* JSAMPLEs per output row */
}
ppm_dest_struct;

typedef ppm_dest_struct *ppm_dest_ptr;

/*
 * For 12-bit JPEG data, we either downscale the values to 8 bits
 * (to write standard byte-per-sample PPM/PGM files), or output
 * nonstandard word-per-sample PPM/PGM files.  Downscaling is done
 * if PPM_NORAWWORD is defined (this can be done in the Makefile
 * or in jconfig.h).
 * (When the core library supports data precision reduction, a cleaner
 * implementation will be to ask for that instead.)
 */

#if BITS_IN_JSAMPLE==8
#define PUTPPMSAMPLE(ptr,v)  *ptr++=(char) (v)
#define BYTESPERSAMPLE 1
#define PPM_MAXVAL 255
#else
#ifdef PPM_NORAWWORD
#define PUTPPMSAMPLE(ptr,v)  *ptr++=(char) ((v) >> (BITS_IN_JSAMPLE-8))
#define BYTESPERSAMPLE 1
#define PPM_MAXVAL 255
#else
/* The word-per-sample format always puts the LSB first. */
#define PUTPPMSAMPLE(ptr,v)			\
	{ register int val_=v;		\
		*ptr++=(char) (val_ & 0xFF);	\
		*ptr++=(char) ((val_ >> 8) & 0xFF);	\
	}
#define BYTESPERSAMPLE 2
#define PPM_MAXVAL ((1<<BITS_IN_JSAMPLE)-1)
#endif
#endif

METHODDEF(void)
sanei_jpeg_start_output_ppm(j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
{
	cinfo = cinfo;
	dinfo = dinfo;
	/* header image is supplied for us */

}

METHODDEF(void)
sanei_jpeg_finish_output_ppm(j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
{
	cinfo = cinfo;
	dinfo = dinfo;

	/* nothing to do */
}

/*
 * Write some pixel data.
 * In this module rows_supplied will always be 1.
 *
 * put_pixel_rows handles the "normal" 8-bit case where the decompressor
 * output buffer is physically the same as the fwrite buffer.
 */

METHODDEF(void)
sanei_jpeg_put_pixel_rows(j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
			  JDIMENSION rows_supplied, char *data)
{
	ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
	cinfo = cinfo;
	dinfo = dinfo;
	rows_supplied = rows_supplied;

	memcpy(data, dest->iobuffer, dest->buffer_width);
}


/*
 * This code is used when we have to copy the data and apply a pixel
 * format translation.  Typically this only happens in 12-bit mode.
 */

METHODDEF(void)
sanei_jpeg_copy_pixel_rows(j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
			   JDIMENSION rows_supplied, char *data)
{
	ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
	register char *bufferptr;
	register JSAMPROW ptr;
	register JDIMENSION col;

	cinfo = cinfo;
	dinfo = dinfo;
	rows_supplied = rows_supplied;

	ptr = dest->pub.buffer[0];
	bufferptr = dest->iobuffer;
	for (col = dest->samples_per_row; col > 0; col--) {
		PUTPPMSAMPLE(bufferptr, GETJSAMPLE(*ptr++));
	}
	memcpy(data, dest->iobuffer, dest->buffer_width);
}


/*
 * Write some pixel data when color quantization is in effect.
 * We have to demap the color index values to straight data.
 */

METHODDEF(void)
sanei_jpeg_put_demapped_rgb(j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
			    JDIMENSION rows_supplied, char *data)
{

	ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
	register char *bufferptr;
	register int pixval;
	register JSAMPROW ptr;
	register JSAMPROW color_map0 = cinfo->colormap[0];
	register JSAMPROW color_map1 = cinfo->colormap[1];
	register JSAMPROW color_map2 = cinfo->colormap[2];
	register JDIMENSION col;

	rows_supplied = rows_supplied;

	ptr = dest->pub.buffer[0];
	bufferptr = dest->iobuffer;
	for (col = cinfo->output_width; col > 0; col--) {
		pixval = GETJSAMPLE(*ptr++);
		PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map0[pixval]));
		PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map1[pixval]));
		PUTPPMSAMPLE(bufferptr, GETJSAMPLE(color_map2[pixval]));
	}
	memcpy(data, dest->iobuffer, dest->buffer_width);
}


METHODDEF(void)
sanei_jpeg_put_demapped_gray(j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
			     JDIMENSION rows_supplied, char *data)
{
	ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
	register char *bufferptr;
	register JSAMPROW ptr;
	register JSAMPROW color_map = cinfo->colormap[0];
	register JDIMENSION col;

	rows_supplied = rows_supplied;

	ptr = dest->pub.buffer[0];
	bufferptr = dest->iobuffer;
	for (col = cinfo->output_width; col > 0; col--) {
		PUTPPMSAMPLE(bufferptr,
			     GETJSAMPLE(color_map[GETJSAMPLE(*ptr++)]));
	}
	memcpy(data, dest->iobuffer, dest->buffer_width);
}

GLOBAL(djpeg_dest_ptr)
	sanei_jpeg_jinit_write_ppm(j_decompress_ptr cinfo)
{

	ppm_dest_ptr dest;

	/* Create module interface object, fill in method pointers */
	dest = (ppm_dest_ptr)
		(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
					    SIZEOF(ppm_dest_struct));
	dest->pub.start_output = sanei_jpeg_start_output_ppm;
	dest->pub.finish_output = sanei_jpeg_finish_output_ppm;

	/* Calculate output image dimensions so we can allocate space */
	jpeg_calc_output_dimensions(cinfo);

	/* Create physical I/O buffer.  Note we make this near on a PC. */
	dest->samples_per_row =
		cinfo->output_width * cinfo->out_color_components;
	dest->buffer_width =
		dest->samples_per_row * (BYTESPERSAMPLE * SIZEOF(char));
	dest->iobuffer = (char *) (*cinfo->mem->alloc_small)
		((j_common_ptr) cinfo, JPOOL_IMAGE, dest->buffer_width);

	if (cinfo->quantize_colors || BITS_IN_JSAMPLE != 8 ||
	    SIZEOF(JSAMPLE) != SIZEOF(char))
	{
		/* When quantizing, we need an output buffer for clrmap indexes
		 * that's separate from the physical I/O buffer.  We also need a
		 * separate buffer if pixel format translation must take place.
		 */
		dest->pub.buffer = (*cinfo->mem->alloc_sarray)
			((j_common_ptr) cinfo, JPOOL_IMAGE,
			 cinfo->output_width * cinfo->output_components,
			 (JDIMENSION) 1);
		dest->pub.buffer_height = 1;
		if (!cinfo->quantize_colors)
			dest->pub.put_pixel_rows = sanei_jpeg_copy_pixel_rows;
		else if (cinfo->out_color_space == JCS_GRAYSCALE)
			dest->pub.put_pixel_rows =
				sanei_jpeg_put_demapped_gray;
		else
			dest->pub.put_pixel_rows =
				sanei_jpeg_put_demapped_rgb;
	} else {
		/* We will fwrite() directly from decompressor output buffer. */
		/* Synthesize a JSAMPARRAY pointer structure */
		/* Cast here implies near->far pointer conversion on PCs */
		dest->pixrow = (JSAMPROW) dest->iobuffer;
		dest->pub.buffer = &dest->pixrow;
		dest->pub.buffer_height = 1;
		dest->pub.put_pixel_rows = sanei_jpeg_put_pixel_rows;
	}

	return (djpeg_dest_ptr) dest;
}
